In my opinion, the main appeal of UBI over other forms of support is that
- the absence of means testing ensures no one falls through the cracks, and
- you never earn less by working harder.
That's not to say that you can't design a support system that doesn't have these issues, but with UBI, they're just trivially non-existent. No need for extra work in figuring out how to fix these problems.
I don't see how funding would be an issue unless you count the savings from letting people fall through the cracks. Shouldn't it cost the same to effectively support people in need regardless of how you distribute the money?
I'm talking about various social benefits like welfare or disability that would ideally be replaced by a UBI.
I hear a lot of stories about this but I don't remember if they're Canadian or not; There's a lot of people who are on disability and are still capable of doing part time work or taking care of their kids for an hour every day for example, but they can't because if they're found doing anything, they lose all of their disability benefits. We want a system that allows them to do what they can and be rewarded for contributing to the best of their abilities rather than punishing them for it.
It's the same deal with welfare. You need to hit a certain income threshold before your take-home income surpasses what you'd get through welfare. Until then, you're putting a bunch of energy into working to make less money when you could be lounging at home and making more. This actively discourages people from bettering their lives.